TPO antibody status prior to first radioactive iodine therapy as a predictive parameter for hypothyroidism in Graves’ disease

Abstract

Objective We investigated if a positive thyroid peroxidase antibody (TPO Ab) status before radioactive iodine (RAI) therapy in patients with Graves’ hyperthyroidism is a predictive factor for developing hypothyroidism post RAI. Methods We performed a retrospective study of patients with Graves’ hyperthyroidism with known TPO Ab status, receiving a first administration of RAI. Patients from 4 thyroid outpatient centres in Belgium receiving a first RAI therapy between the years 2011 and 2019 were studied. Clinical, laboratory, imaging, and treatment data were recorded from medical charts. Hypothyroidism and cure (defined as combined hypo- and euthyroidism) were evaluated in period 1 (≥2 and ≤9 months, closest to 6 months post RAI) and period 2 (>9 months and ≤ 24 months post RAI, closest to 12 months post RAI). Results One hundred fifty-two patients were included of which 105 (69%) were TPO Ab positive. Compared to TPO Ab negative patients, TPO Ab positive patients were younger, had a larger thyroid gland, and had more previous episodes of hyperthyroidism. In period 1, 89% of the TPO Ab positive group developed hypothyroidism versus 72% in the TPO Ab negative group (p=0.007). In period 2, the observation was similar: 88% vs. 72% (p=0.019). In the multivariate logistic regression analysis, a positive TPO Ab status was associated with hypothyroidism in period 2 (adjusted OR 4.78 (95% CI 1.27-20.18;p=0.024). In period 1, the aOR was 4.16 (95% CI 1.0-18.83; p=0.052). Conclusion A positive TPO Ab status in patients with Graves’ hyperthyroidism receiving a first administration of RAI is associated with a higher risk of early hypothyroidism.

Blood Profiles in the Prediction of Radioiodine Refractory Papillary Thyroid Cancer: A Case–Control Study

“…In most cases, TPO-Ab was tested to evaluate the incidence of Hashimoto's thyroiditis after I-131 ablation. 55,56 In this study, the slight elevation of TPO-Ab might be attributed to the increasing apoptosis of thyroid cancer cells and the subsequent release of TPO into circulation due to I-131 damage.…”

The Role of Thyroid Antibodies in Thyroid Eye Disease

“…38 Autoimmune thyroid disease, hypothyroid, and euthyroid patients have a high prevalence of TPO-Abs, and their measurement is helpful in the diagnostic workup of these patients. 38 Yet, Khoo et al 39 demonstrated that the absence of thyroid peroxidase antibodies together with high TSI levels in Graves disease identifies a group at a markedly increased risk of ophthalmopathy. Recent studies have proved the therapeutic effect of selenium in TED and it is believed that selenium reduces the TSHR-Ab and TPO-Abs in addition to an inhibitory effect of HLA-DR molecule expression on thyrocytes, prevention of dysregulation of cell-mediated immunity and B-cell function, neutralizing reactive oxygen species, and inhibition of expression of proinflammatory cytokines, prostaglandin, and leukotriene synthesis.…”

“…Also, 10% to 15% of normal individuals can have high levels of TPO-Ab titers 8,37 . TPO is expressed in orbital tissues, and the polymorphism rs11675434 SNP has been proven to be associated with clinically evident TED 38 . Studies in pediatric patients have also shown a positive correlation between high TPO-Ab levels and TED 38 .…”

“…Studies in pediatric patients have also shown a positive correlation between high TPO-Ab levels and TED 38 . Autoimmune thyroid disease, hypothyroid, and euthyroid patients have a high prevalence of TPO-Abs, and their measurement is helpful in the diagnostic workup of these patients 38 . Yet, Khoo et al 39 demonstrated that the absence of thyroid peroxidase antibodies together with high TSI levels in Graves disease identifies a group at a markedly increased risk of ophthalmopathy.…”

“…TPO is expressed in orbital tissues, and the polymorphism rs11675434 SNP has been proven to be associated with clinically evident TED 38 . Studies in pediatric patients have also shown a positive correlation between high TPO-Ab levels and TED 38 . Autoimmune thyroid disease, hypothyroid, and euthyroid patients have a high prevalence of TPO-Abs, and their measurement is helpful in the diagnostic workup of these patients 38 .…”